The present invention relates to an electronic circuit for driving a current-driven element, such as an organic light-emitting diode element, a method of driving the electronic circuit, an electro-optical device, and an electronic apparatus.
In recent years, as a next-generation light-emitting element that replaces liquid crystal elements, an organic light-emitting diode element (hereinafter, suitably referred to as ‘OLED element’) called as an organic electroluminescent element or a light-emitting polymer element has been drawing a considerable attention. The OLED element has a low viewing angle dependency because it is a self-emitting type. Further, because the backlight or reflected light is not required, the OLED element has excellent characteristics such as low power consumption and a reduced thickness as a display panel.
Here, the OLED element is a current-driven element in which the light emission state cannot be held when the current is disrupted, without having the voltage maintenance property, unlike the liquid crystal devices. For this reason, in the case of driving the OLED element in an active matrix manner, a configuration that a voltage according to the gray-scale level of the pixel is written onto the gate of a driving transistor to hold the voltage by a gate capacitance or the like in a writing period (a selection period) is used, in which the driving transistor continuously flows the current according to the gate voltage into the OLED element.
However, in this configuration, there is a problem in that the threshold voltage characteristic of the driving transistor is deviated, and thus the brightness of the OLED element varies in each pixel to consequently deteriorate the display quality. For this reason, recently, a technology has been suggested, in which the driving transistor is brought into diode connection and the constant current flows from the driving transistor into a data line, such that the voltage according to the current flowing into the OLED element is written onto the gate of the driving transistor so as to compensate the deviation of the threshold voltage characteristic of the driving transistor (for example, see Patent Documents 1 and 2).
[Patent Document 1] U.S. Pat. No. 6,229,506 (see FIG. 2)
[Patent Document 2] Japanese Unexamined Patent Publication No. 2003-177709 (see FIG. 3)
However, in this technology, in the case of using an N-channel driving transistor, when the current flowing into the OLED element is set to become small, the gate voltage of the driving transistor is low and it is difficult to flow the current between the source and the drain of the driving transistor, in the writing period. Accordingly, there is a problem in that the required voltage cannot be written onto the gate of the driving transistor in the writing period.
Accordingly, the present invention has been made in consideration of the above-mentioned problems, and it is an object of the present invention to provide an electronic circuit, in which a voltage according to a current flowing into a driven element can be quickly written onto the gate of the driving transistor, a method of driving the electronic circuit, an electro-optical device using the electronic element, and an electronic apparatus.